As is well known, car washing is carried out by covering the vehicle with detersive foam, following mechanical brushing and rinsing.
The first step of this task requires a foam supply applied at considerable pressure to reach the points most distant from the outlet and also abundant flow to achieve quick covering to activate the process: but this is not what occurs in practice because the machines used at present produce suction of active matter and air, and the ejection of foam formed by an electrical pump, such method being insufficient to achieve the ideal conditions of flow and pressure.
On the other hand, these machines require a rigorous control due to the presence of electrical circuits in highly humid environments as are wash tunnels.